The present invention relates in general to network communications and, more specifically, to a method and system for providing an active routing antenna for use in conjunction with fixed and mobile wireless transceivers with dynamic routing based on quality-of-service (QoS) criteria in order to optimize data transfers in a network with dynamically changing topology.
Wireless networks are gaining in popularity. Standards such as IEEE 802.11a, 802.11b, 802.11 g, Bluetooth, Ultra Wideband (UWB), etc., allow users to connect wirelessly via portions of the radio-frequency spectrum. As the cost of wireless network systems decreases and their popularity increases, these systems are becoming more prevalent. Some provide channels for relatively unrestricted transfer of information among various devices. The devices can be owned or operated by different users without formal licensing registration, certification, administrator approval or other access restrictions. In cases where mobile wireless transceivers are used, there can be a constant change in the number and type of devices accessing a wireless network.
The types of wireless systems available today have shortcomings for some applications. The IEEE 802.11a, 802.11b and 802.11 g standard systems have two modes of operation: infrastructure and Ad-Hoc. The infrastructure mode uses a dedicated radio controller and is primarily designed to provide a direct wireless link to a standard Ethernet network connection. The “Ad Hoc” approach allows for peer-to-peer networking, so that a very small network of several PCs on the same wireless channel can share files. The nodes in this network control their own access to the wireless media. The Ad Hoc mode is primarily used to temporarily interconnect a few computers together where an Ethernet backbone may not be available or an emergency network is required. There is no means of gaining access to the corporate Ethernet network or an Internet connection. As such, neither scheme is designed for “multi-hop” transmission. In a “multi-hop” scheme, data is transferred to intermediary wireless transceivers before arriving at a final target receiving device.
Generally, the quality of a communications channel in a wireless network is not guaranteed so that, for example, a software process executing on a device is not guaranteed a specific transfer rate over any given interval of time. This makes it very difficult to provide, e.g., streaming media such as video and audio.
Other approaches to wireless communications do not provide a comprehensive system design approach. For example, UWB only defines a radio physical layer. This merely defines how bits will be transmitted on the radio interface physical connection. There is no definition for a flexible protocol to allow coordination of devices, channels, links, etc., within a UWB wireless network. Bluetooth does include several features for point-to-point communications between devices, but does this based on a master-slave relationship that is difficult to use in a network with changing topology, such as one made up of mobile wireless transceivers. In addition, all the nodes within the Bluetooth network must be able to communicate at least with the master for coordination purposes. This clearly limits the operational range of the network.
Other considerations for a flexible wireless communication system include scalability, range, coverage, user interface presentation and options, network management, minimization of radio interference, compliance with applicable regulations, creation of user features to generate market desirability, security and access controls, physical design, features and operation of the devices, etc.
Furthermore, wireless communications are typically implemented using radio frequency (RF). Typically, a radio network is made up of a number of base transmitting stations (BTSs), each connected to a wired network. Each BTS provides a region of RF coverage (also called cells) for users of the network. The radio frequencies used by the BTSs may be in a licensed or ISM band. Devices then communicate with the wired network using the radio frequency associated with a BTS. Adjoining BTSs may use different frequencies to improve use of the radio resources.
The radio network as described above suffers from a number of shortcomings. These shortcomings include, for example, link inefficiency, security problems, roaming issues and network deployment issues.
With respect to link inefficiency, most of the current radio technologies rely on a Media Access Control (MAC) layer to provide shared access to the radio media. However, the current MAC layers are designed to deal with a single point-to-point link, that is, one mobile user/terminal device in communication with one BTS radio link. This leads to a number of problems in the design of the MAC layer. For example, the MAC layer is not designed to coordinate transmissions from multiple BTSs, or peer nodes, but only terminal devices. The MAC layer also does not generally provide any quality of service functions, since it is not required to by the nature of the communication link. In addition, in some networks, the MAC layer must sense the radio media before transmission, which means that the best link may not be utilized.
With respect to network security, the radio network is inherently a shared medium. Hence, anyone equipped with suitable receiver equipment can eavesdrop on the network. Many attempts have been made to prevent eavesdropping, for example, by encrypting the radio link based on some shared key or other algorithm. In public cellular systems, the keys are usually generated and stored in a central database, which can lead to security problems with respect to access. Other techniques that have been used include end-to-end encryption using IPSec or secure shells. However, these techniques require software to run above the radio connection and must also be run by the user prior to any communication between the user and the network.
With respect to roaming, handover techniques could be used in a radio network to allow the user to roam within the bounds of the network. However, the problem remains that as the user moves from one BTS to another, the point of attachment to the network changes. In an IP network, this may mean that the subnet that the user is originally registered on may change thereby leading to loss of connection. Existing solutions to this problem mainly rely on the use of mobile IP and its variants. These solutions remain unsatisfactory in that as the user moves around more and more, nodes in the network may become tied up with carrying traffic that is merely transiting the node and not terminating the IP traffic, thereby leading to very inefficient use of network resources. Some such solutions may attempt to clear up the network trails but may also provide disruption problems for real time traffic.
With respect to network deployment, in order to provide radio network coverage, it is generally necessary for the operator of the network to install BTSs in areas to provide coverage and then to link these BTSs back to the main network. This can be an expensive and time-consuming process. Furthermore, the positioning of the BTSs is generally dictated by physical constraints of the locale and may be suboptimal.
An alternative to the Fixed BTS-Mobile Terminal network architecture is an “Ad Hoc” wireless network. In this type of network, many or all the nodes of the network could be in motion. Consequently, it is difficult to know the relative location of the two wireless nodes that may wish to communicate. Hence, it is also difficult to determine a “best path” to the destination or recipient node without generally flooding the network with route requests the essentially search every possible path for a route to the destination. The foregoing method of establishing links between two wireless nodes is very inefficient, wasting a large amount of bandwidth in the process. In addition, the foregoing method also limits the number of nodes that could be supported. In effect, the network becomes self-limiting because of the lack of node location information.
In order to improve the performance of an ad hoc network, it is possible to provide location information to various wireless nodes using, for example, the Global Positioning System (GPS). Use of GPS, however, is generally quite expensive in terms of product cost and power drain on each node. In addition, GPS has certain coverage limitations which prevent it from being used in some physical locations, such as, inside a building structure.
Hence, it would be desirable to provide a wireless network with dynamically changing topology that is capable of accommodating and handling heterogeneous user traffic from multiple devices in a more efficient manner.